Data from: Logging-induced changes in habitat network connectivity shape behavioral interactions in the wolf-caribou-moose system

Habitat connectivity influences the distribution dynamics of animals. Connectivity can therefore shape trophic interactions, but little empirical evidence is available, especially for large mammals. In forest ecosystems, logging alters functional connectivity among habitat patches, and such activities can affect the spatial game between large herbivores and their predators. We used graph theory to evaluate how harvesting-induced changes in habitat connectivity influence patch choice and residency time of GPS-collared caribou (Rangifer tarandus caribou) and moose (Alces alces) in winter in the boreal forest. We then investigated the predator–prey game by assessing how GPS-collared wolves (Canis lupus) adjusted their movements to changes in landscape properties and in the networks of their prey species. We built prey habitat networks using minimum planar graphs organized around species-specific, highly selected habitat patches (i.e., network nodes). We found that spatial dynamics of large herbivores were influenced not only by the intrinsic quality of habitat patches, but also by the connectivity of those network nodes. Caribou and moose selected nodes that were connected by a high number of links, and moose also spent relatively more time in those nodes. By limiting node accessibility, human disturbances influenced travel decisions. Caribou and moose avoided nodes that were surrounded by a high proportion of cuts and roads, but once within these nodes, moose stayed longer than in other nodes. Caribou selectively moved among nodes with low distance costs, and their residency time increased with distance costs required to reach the nodes. Wolves selected their prey's nodes, where vegetation consumed by caribou and moose was highly abundant. Furthermore, wolves discriminated among those nodes by selecting the most connected ones. In fact, selection by wolves was stronger for their prey's nodes than for the prey's utilization distribution per se, a difference that increased with the level of human disturbance. Considering the difficulty of keeping track of highly mobile prey, predators may benefit by targeting not only their prey's resource patches, but also the most highly connected patches. Matrix quality and connectivity are therefore key elements shaping the predator–prey spatial game in human-altered landscapes because of their impact on the spatial dynamics of the interacting species.

生境连通性（habitat connectivity）会影响动物的分布动态。因此，连通性可塑造营养级互作，但目前相关实证研究证据较为匮乏，针对大型哺乳动物的研究尤为不足。森林生态系统中，伐木活动会改变生境斑块间的功能连通性（functional connectivity），进而干扰大型植食动物与其捕食者之间的空间博弈（spatial game）。本研究借助图论（graph theory），评估了采伐活动诱导的生境连通性变化，如何影响北方针叶林（boreal forest）冬季环境中，佩戴GPS项圈的北美驯鹿（Rangifer tarandus caribou）与驼鹿（Alces alces）的斑块选择行为及停留时长。随后，本研究通过分析佩戴GPS项圈的灰狼（Canis lupus）如何根据景观属性与猎物种群网络的变化调整移动路径，探究了捕食者-猎物博弈（predator–prey game）机制。我们以物种特异性的高偏好生境斑块（即网络节点，network nodes）为核心单元，采用最小平面图（minimum planar graphs）构建了猎物的生境网络。研究发现，大型植食动物的空间动态不仅受生境斑块的固有质量影响，同时也取决于这些网络节点的连通性水平。北美驯鹿与驼鹿均会选择连通边数量较多的网络节点，且驼鹿在这类节点中的停留时长相对更长。人类活动干扰通过限制节点可达性，对动物的移动决策产生影响。北美驯鹿与驼鹿会避开周边存在大量采伐迹地与道路的节点，但一旦进入这类节点，驼鹿的停留时间反而长于其他节点。北美驯鹿会选择性地在距离成本（distance costs）较低的节点间移动，且其停留时长随抵达节点所需的距离成本增加而延长。灰狼会选择其猎物所在的节点，即北美驯鹿与驼鹿的取食植被分布较为丰富的节点。此外，灰狼还会在这类节点中进一步筛选，优先选择连通性最高的节点。事实上，灰狼对猎物种节点的选择强度，高于其对猎物自身利用分布的选择强度，且这一差异随人类干扰程度的加剧而愈发明显。鉴于追踪高度移动的猎物存在难度，捕食者若同时瞄准猎物的资源斑块与连通性最高的斑块，将更利于自身觅食。因此，景观基质质量与连通性是调控人类干扰景观中捕食者-猎物空间博弈的核心要素，因其会直接影响交互物种的空间动态。